In recent years, ferroelectric random access memory (FeRAM) capable of keeping information in a ferroelectric capacitor structure making use of ferroelectric domain inversion has been developed. The ferroelectric random access memory is a non-volatile memory capable of keeping information unerased even if power supply is interrupted, and attracts much attention with expectations of realizing high degree of integration, high-speed operation, high durability and low power consumption.
Materials widely used for ferroelectric film composing the ferroelectric capacitor structure includes ferroelectric oxides having perovskitic crystal structure such as PZT (Pb(Zr,Ti)O3) film, SBT (SrBi2Ta2O9) film and so forth, having large residual polarization typically from 10 (μC/cm2) to 30 (μC/cm2) or around.
[Patent Document 1]    Japanese Patent Application Laid-Open No. H1-253940
[Patent Document 2]    Japanese Patent Application Laid-Open No. S54-139469
[Patent Document 3]    Japanese Patent Application Laid-Open No. S62-32636
[Patent Document 4]    Japanese Patent Application Laid-Open No. H2-165646